RNA甲基化在肾脏衰老中的作用及其分子机制研究

Epigenetic regulation is an important mechanism related to aging and degeneration of kidney. RNA methylation is the latest progress in epigenetics, and affects protein expression more directly than DNA methylation. Our previous study found that the content of RNA m6A in aging kidneys was significantly up-regulated, and the corresponding key regulatory enzyme was METTL14. Klotho and SIRT1 are important anti-aging genes, but their upstream regulation mechanism is still unclear. Therefore, it is hypothesized that METTL14 regulates the expression of Klotho and SIRT1 genes through RNA m6A modification, and participates in the process of renal aging. On the basis of our previous work, we intend to systematically elucidate the role of RNA m6A in the development of kidney aging and its regulatory mechanism by using gene knockout and overexpression techniques at both cellular and animal levels, and then reveal the mechanism of kidney aging from METTL14-RNA m6A, a new gene regulatory pathway, which may be expected to delay kidney aging and provide new targets.

肾脏随着增龄发生渐进性衰老。研究证实表观遗传调控在肾脏衰老过程中发挥重要作用，而RNA甲基化是表观遗传学最新进展，且较DNA甲基化等修饰方式更为直接地影响蛋白表达，但在肾脏衰老中的作用尚不明确。我们前期研究发现衰老肾脏RNA m6A含量显著上调，并初步筛选出可能的RNA m6A修饰调控酶METTL14；同时在原代肾小管上皮细胞衰老模型中发现，衰老相关基因Klotho的m6A甲基化水平显著增加。因此提出假设：METTL14通过调控RNA m6A修饰，调节衰老相关基因Klotho、SIRT1蛋白表达，参与肾脏衰老过程。我们拟在前期工作基础上，从细胞和动物两个层面，采用肾小管条件性基因敲除、基因沉默和过表达等技术，系统阐明RNA m6A在肾脏衰老发生发展中的作用及其调控机制，进而从METTL14-RNA m6A-衰老相关基因这一新的信号途径揭示肾脏衰老机制，为延缓肾脏衰老提供新靶点和新思路。

肾脏随着增龄发生渐进性衰老。研究证实表观遗传调控在肾脏衰老过程中发挥重要作用，而RNA甲基化是重要的转录后调控，且较DNA甲基化等修饰方式更为直接地影响蛋白表达，但在肾脏衰老中的作用尚不明确。我们研究发现衰老肾脏RNA m6A含量显著上调，并初步筛选出可能的RNA m6A修饰调控酶METTL14及识别蛋白YT HDF1在老年组肾脏组织中显著高表达；高通量MeRIP-seq分析了两组肾组织mRNA m6A甲基转录组及转录组。RNA-seq揭示了与肾脏衰老相关的差异表达基因。在机制上，我们确定炎症标记物Toll样受体4（TLR4）是肾脏衰老过程中m6A的下游靶点。我们发现YTHDF1可以增强TLR4的mRNA稳定性，并促进蛋白质表达。在体外，过表达YTHDF1显著抑制HK2细胞的活力。这一新的信号途径揭示肾脏衰老机制，为延缓肾脏衰老提供新靶点和新思路。同时我们研究了m6A在足细胞损伤中的作用机制，同样发现阿霉素肾病和糖尿病肾病小鼠肾脏中m6A RNA水平显著升高，METTL14表达显著上调。足细胞特异性METTL14敲除可改善肾小球功能，减轻足细胞损伤，其机制可能是METTL14依赖性RNA m6A修饰通过转录后调节Sirt1 mRNA而导致足细胞损伤，同时激活自噬，抑制ADR肾病小鼠的凋亡和炎症，从而为足细胞损伤的诊断和治疗提供了一种潜在的方法。